Interleukin-1β processing is dependent upon a calcium-mediated interaction with calmodulin.

Joseph Ainscough, G Frank Gerberick, Ian Kimber, Rebecca J Dearman

    Research output: Contribution to journalArticlepeer-review


    The secretion of IL-1β is a central event in the initiation of inflammation. Unlike most other cytokines, the secretion of IL-1β requires two signals; one signal to induce the intracellular up-regulation of pro-IL-1β, and a second signal to drive secretion of the bioactive molecule. The release of pro-IL-1β is a complex process involving proteolytic cleavage by caspase-1. However, the exact mechanism of secretion is poorly understood. Here, we sought to identify novel proteins involved in IL-1β secretion and intracellular processing in order to gain further insight into the mechanism of IL-1 release. A human proteome microarray containing 19,951 unique proteins was used to identify proteins that bind human recombinant pro-IL-1β. Probes with a signal to noise ration of >3 were defined as relevant biologically. In these analyses, calmodulin was identified as a particularly strong hit, with a SNR of ~11. Using an ELISA-based protein-binding assay, the interaction of recombinant calmodulin with pro-IL-1β, but not mature IL-1β, was confirmed and shown to be calcium dependent. Finally, using small molecule inhibitors it was demonstrated that both calcium and calmodulin were required for nigericin induced IL-1β secretion in THP-1 cells and primary human monocytes. Together, these data suggest that following calcium influx into the cell, pro-IL-1β interacts with calmodulin and that this interaction is important for IL-1β processing and release.
    Original languageEnglish
    Pages (from-to)31151-31161
    JournalThe Journal of biological chemistry
    Issue number52
    Publication statusPublished - 11 Nov 2015


    • IL-1β
    • calcium
    • calmodulin (CaM)
    • caspase 1 (CASP1)
    • inflammasome
    • interleukin 1 (IL-1)


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